Problem: On the first 5 exams of her physics class, Gabriela got an average score of 80. What does she need on the next exam to have an overall average of 82?
Answer: Let her score on the next exam be $x$ The sum of all of her scores is then $5 \cdot 80 + x$ The same sum must also be equal to $6 \cdot 82$ Solve: $x = 6 \cdot 82 - 5 \cdot 80 = 92$.